The present invention relates to a method of providing subscribers with ring signal service in an exchange system, and more particularly a method of automatically and equally distributing the ring signal to a plurality of subscribers with a ring signal generator of small capacity.
Generally, the ring signal generator 10 of an exchange system in FIG. 1 is connected to a subscriber circuit 20 to supply the ring signal to one or a plurality of telephones ST1-STm under control of a central processing unit (CPU) module 30.
Referring to FIG. 2 for representing an exemplified waveform of a fundamental ring signal, an interval ON represents a time duration connecting the ring signal, and a next interval OFF another time duration disconnecting the ring signal. A control signal from the CPU module 30 is decoded by a decoder 50, whereby ring service control data from the CPU module 30 are latched by addressable latch 40 to control on/off of ring relays RYl-RYn. Namely, the addressable latch 40 latches the output data of the CPU module 30 to switch the relays RYl-RYn on or off, whereby supplying of the ring signal is controlled.
Since a ring current should be supplied from the ring signal generator 10 to any one of the subscriber telephones ST1-STn to provide the ring service in a specified time period such as T1 to T2, T3 to T4 and so on, as shown in FIG. 3, an amount of the ring current to be supplied depends on a number of the subscriber telephones ST1-STn to be serviced. Therefore, as increases the number of the subscribers to be served, also increases the quantity of the ring current of the ring signal generator 10. This large amount of the ring current often results in waste of electric power in the exchange system.